The present invention relates to a roller support apparatus and, more particularly, to a roller support apparatus provided to an inking device or dampening unit of a printing press to maintain the a contact pressure between two contacting rollers at a constant value.
In an inking device for an offset printing press, to uniform the thickness of ink to be supplied, a rubber roller and metal roller (an iron roller or a roller having a surface made of a hard metal such as copper) are rotated while their outer surfaces are in contact with each other, thus distributing the ink. According to this arrangement, the diameter of the rubber roller in contact with the metal roller changes due to wear or the like, leading to a change in contact pressure, i.e., nip pressure, between the rollers. When the nip pressure changes, the ink film thickness changes to largely adversely affect the printing quality. Therefore, conventionally, the inking device is provided with an adjustment unit which adjusts the nip pressure.
As shown in Japanese Patent Laid-Open No. 9-39211, a conventional roller support apparatus includes a support member which supports a distribution roller to be movable in directions to come close to and separate from an oscillating roller which is in contact with the distribution roller, a biasing member which biases the support member in a direction to urge the distribution roller against the oscillating roller, and a moving means for moving the distribution roller in the direction to separate from the oscillating roller against the biasing force of the biasing member.
In the conventional roller support apparatus described above, the biasing force of the biasing member is directly utilized without using a mechanism (amplification mechanism) that increases the biasing force. Hence, the biasing force itself of the biasing member must be large. In addition, in order to move the distribution roller in the direction to separate from the oscillating roller, the moving means is moved in the direction to accumulate the biasing force of the biasing member. The operation is thus cumbersome and time-consuming.